Reciprocating liquid pumps



March 17, 1970 R. T. J. SKINNER 3,500,753

RECIPROCATING LIQUID PUMPS Filed April 12, 1968 v 2 Sheets-Sheet 1 March 17, 1970 J, sKlNNER 3,500,758

RECIPROCATING LIQUID PUMPS Filed April 12, 1968 2 Sheets-Sheet 2 Z6 Z? I 24 United States Patent Ofice 3,500,758 Patented Mar. 17, 1970 3,500,758 RECIPROCATING LIQUID PUMPS Robert Thomas John Skinner, Kenilworth, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Filed Apr. 12, 1968, Ser. No. 720,784 Int. Cl. F04b 1/00, 21 04, 9/06 US. Cl. 103171 3 Claims ABSTRACT OF THE DISCLOSURE The object of the present invention is to provide a. reciprocating liquid pump in a convenient form.

According to the present invention a reciprocating liquid pump comprises, in combination, a casing having an inlet for liquid to be pumped, a driving shaft extending into the casing, eccentric means in the casing rotatable by the shaft, a pair of piston and cylinder devices disposed in the casing at opposite sides of the eccentric means, one part of each of the piston and cylinder devices being movable with the eccentric means and the other part being fixed relative to the casing, a resilient coupling between the movable parts of the pair of piston and cylinder de vices whereby said movable parts are urged towards their respective sides of the eccentric means, a pair of nonreturn valves for permitting fiow of liquid from the easing into the inner ends of the pair of cylinders respectively, and outlets from the pair of cylinders respectively.

A specific example of the present invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is a cross-sectional view of a fuel injection device connected to a pump constructed in accordance with this invention,

FIGURE 2 is a cross-sectional view of the pump, on the line II--II in FIGURE 1, and

FIGURE 3 is a fragmentary cross-sectional view showing outlet passages from the pump to the fuel injection device.

In this example of the invention there is provided a liquid pump for use in conjunction with a fuel (for example petrol) injection device indicated generally at 10 such as that described in the complete specification of our copending British patent application No. 13,800/64. This device comprises a distributor disc 11 mounted for rotation in a body 12, the latter having inlets 13 for the flow of fuel to the disc 11. The disc 11 and the body 12 have respective passages for permitting flow of fuel to a cylindrical bore 14 containing a shuttle 15. Fuel is delivered through further passages in the body 12 and disc 11 by reciprocation of the shuttle 15 to nozzles in an internal combustion engine with which the device is associated. The fuel injection device has a driving shaft 16 which is rotatable by the engine at half engine speed.

The pump of the present invention is provided in a casing 17 which is adapted to be secured to the body 12 of the injection device 10 and the driving shaft 16 of that device also serves to drive the pump and has an extension 18 on the side of the pump casing 17 remote from the fuel injection device 10 whereby it can be driven by the engme.

Within the casing 17 an eccentric 19 is mounted on the shaft 16, this eccentric being enclosed in a rectangular block 20. Rotation of the shaft 16 results in rotation of the eccentric 19 in the block 20 which is thus reciprocated in two mutually perpendicular planes at right angles to the axis of the shaft 16. Against two opposite end faces of the block 20 are a pair of plates 21, 22 respectively. On the opposite side of the plates 21, 22 from the block 20, and within the casing 17 are a pair of U-shaped members 23, 24 respectively, the open ends of which are flanged and drilled to receive respective rods 25, 26 which also pass through aligned holes in the plates 21, 22. These rods 25, 26 each extend through both plates 21, 22 and both U shaped members 23, 24 and are disposed on opposite sides of the block 20 respectively. The rods 25, 26 which extend adjacent to and generally parallel to the limbs of the U- shaped members 23, 24 carry respective coiled compression springs 27 and, at their extreme ends, respective captive abutment washers 28 for these springs.

The mid-portions of the U-shaped members 23, 24 carry respective pistons 29, 30 extending towards the driving shaft 16, these pistons being slidable in respective cylinders 31, 32 secured to the casing 17. The pistons 29, 30 have respective passages 33, 34 extending therethrough, each passage 33, 34 containing a non-return valve arranged to permit flow into the inner end of the cylinders 31, 32 from the interior of the casing 17 but not in the reverse direction, the non-return valves each, in this example, comprising a nylon ball 35 freely movable in a cage formed in the wall of the passage 33 or 34 in the piston, to define a seating 36 for the ball 35.

The inner end of each cylinder 31, 32 has an outlet orifice 37 as seen in FIGURE 3, the orifice containing a non-return valve 38. These outlet orifices 37 are in communication with the inlets 13 in the body 12 of the fuel injection device 10. An inlet 39 is provided in the pump casing 17 for the supply of fuel to the interior of that casing.

In operation, fuel is supplied to the interior of the easing 17 and as the shaft 16 rotates, the pistons 29, 30 slide in their respective cylinders 31, 32. The inertia of the balls 35 of the non-return valves cause opening of these valves to admit fuel to the inner ends of the cylinders 31, 32 as the pistons 29, 30 move outwardly of their cylinders. The movement of the pistons 29, 30 inwardly of the cylinders cause closure of the non-return valves thus forcing the fuel through the outlet orifices 37.

Should the fuel injection device 10 be unable to accept more fuel from the outlet 37, a pressure is built up which prevents the pistons 29, 30 from performing their full travel. This results in the U-shaped members 23, 24 to which the pistons are secured, failing to follow the plates 21, 33 as the block 20 moves with the eccentric 19 on the shaft 16, this being against the action of the springs 27 which thus act to tend to return the U-shaped members 23, 24 into contact with the appropriate plates 21, 22, this only being possible of course when the pressure in the outlet orifice 37 falls below the combined ratings of the springs 28, the pressure reduction being caused by the creation of a demand for fuel at the injection device 10. It will be appreciated that with this arrangement, there is maintained a supply of fuel to the injection device which is always at a minimum pressure equal to the combined ratings of the springs 28.

With this arrangement, the pistons 29, 30 move in respective straight line paths whilst the block 20 moves not only in the plane of these paths, but also in a plane perpendicular to it, the latter movement being sliding motion between the block 20 and the two plates 21, 22.

It will be seen that this pump is capable of delivering fuel at a pressure which is substantially independent of the speed of rotation of the driving shaft.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A reciprocating liquid pump comprising, in combination, a casing having an inlet for liquid to be pumped, a driving shaft extending into the casing, eccentric means in the casing rotatable by the shaft, a pair of piston and cylinder devices disposed in the casing at opposite sides of the eccentric means, one part of the piston and cylinder devices being connected to the eccentric means for movement therewith, and the other part being fixed relative to the casing, a resilient coupling connected between the respective movable parts of the pair of piston and cylin der devices whereby said movable parts are urged towards their respective sides of the eccentric means, a pair of nonreturn valves for permitting flow of liquid from the easing into the inner ends of the pair of cylinders respectively, each non-return valve comprising a ball movably mounted in a cage formed in the movable part of the piston and cylinder device, and outlets from the pair of cylinders respectively.

2. A reciprocating liquid pump according to claim 1 in which the eccentric means comprises an eccentric member mounted on the driving shaft and engageable within a block against which said one part of each of the piston and cylinder devices is spring urged.

3. A reciprocating liquid pump according to claim 1 in which the movable part of each piston and cylinder device is the piston, the piston having a passage in it through which the liquid flows to the inner end of the cylinder, said non-return valve being disposed in said passage.

References Cited UNITED STATES PATENTS 1,079,422 11/1913 McKehnie 103-213 X 1,726,150 8/1929 *Hewitt 103-213 2,542,786 2/1951 Yates et a1. 103-37 2,670,691 3/1954 Guiot 103-150 2,980,023 4/1961 Smith et al 103-211 X 2,442,631 6/ 1948 Winkler 103-178 3,016,843 1/1962 Smith 103-211 FOREIGN PATENTS 602,663 12/ 1925 France.

WILLIAM L. FREEH, Primary Examiner US. Cl. X.R. 103-184, 211 

